The listing or discussion of a prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge. All of the documents referred to in this specification are hereby incorporated by reference.
There is evidence that anti-tumour cytotoxic T lymphocytes (CTL) play an important role in vivo. Tumour reactive CTL have been shown to mediate tumour regression in animal models (Kast et al (1989) Cell 59, 603-614) and in man (Kawakami et al (1994) Proc. Natl. Acad. Sci. USA 91, 6458-6462; Dudley (2002) Science 298, 850-854). As with all types of anti-tumour therapy, a problem that needs to be overcome is that the therapy must destroy or inactivate the target tumour cells to a useful extent but that the therapy must not destroy or inactivate non-tumour cells to a deleterious extent. In other words, it is desirable if the therapy is selective for tumour cells to a beneficial extent.
Much of the current work on immunotherapy of cancer makes use of the fact that certain tumours express polypeptides which are not expressed in the equivalent non-tumour tissue, or makes use of the fact that the tumour expresses a mutant form of a polypeptide which is not expressed in the non-tumour tissue. However, it is not always possible to identify polypeptides in a tumour which fall into this category, and so other target polypeptides which can form the basis of an immunotherapeutic approach have been identified.
In adults, expression of WT1, an embryonic transcription factor, has been observed in renal podocytes, in the testis, in the ovary, in breast myoepithelial cells and in some CD34+ stem cells in the bone marrow. Aberrant expression was observed in breast cancer, ovarian cancer, melanoma, lung cancer, colon cancer, thyroid cancer, head and neck cancer, glioblastoma, sarcoma and leukaemia including CML and AML (see, for example, Menssen et al (1995) Leukaemia 9, 1060-1067; Inoue et al (1997) Blood 89, 1405-1412; Inoue et al (1996) Blood 88, 2267-2278; Inoue et al (1998) Blood 91, 2969-2976; Menssen et al (1997) Int. J. Cancer 70, 518-523; Menssen et al (1995) Leukemia 9, 1060-1067; Ogawa et al (1998) Transplant 21, 527-527; Rodeck et al (1994) Int. J. Cancer 59, 78-82; Silberstein et al (1997) Proc. Natl. Acad. Sci. USA 94, 8132-8137; Tamaki et al (1996) Blood 88, 4396-4398; Viel et al (1994) Int. J. Cancer 57, 515-521; Menssen (2000) J. Cancer Res. Clin. Oncol. 126, 226-232; Miyoshi (2002) Clin. Cancer Res. 8, 1167-1171; Oji (1999) Jpn J. Cancer Res. 90, 194-204; Oji (2003) Cancer Sci. 94, 523-529; Oji et al (2003) Cancer Sci. 94, 606-611; Oji et al (2003) Cancer Sci. 94, 712-717; and Ueda (2003) Cancer Sci. 94, 271-276.
As described in our patent application WO00/26249, using an unconventional approach employing allo-MHC-restricted CTL, we identified peptide epitopes in the WT1 polypeptide which may be presented by HLA-A2 class I molecules and displayed on the surface of tumour cells expressing these proteins endogenously. HLA-A2 negative responder individuals were used as a source of CTL specific for peptides presented by HLA-A2 class I molecule, and this approach allows identification of HLA-A2 presented peptides independent of possible tolerance of autologous CTL.
One of the peptide epitopes disclosed in WO00/26249 is RMFPNAPYL (which we have also termed pWT126), and we have previously described a CTL which is able to: kill HLA-A2-positive targets coated with the WT1-derived peptide pWT126 (Gao et al (2000) Blood 95, 2198-2203); kill fresh HLA-A2-positive leukaemia cells expressing WT1 (Gao et al (2000) Blood 95, 2198-2203); kill HLA-A2-positive leukemia CFU progenitor cells (Gao et al (2000) Blood 95, 2198-2203; Bellantuono et al (2002) Blood 100, 3835-3837); kill HLA-A2-positive leukaemia LTC-IC stem cells (Bellantuono et al (2002) Blood 100, 3835-3837); kill HLA-A2-positive NOD/SCID leukaemia initiating cells (Gao et al (2003) Transplantation 75, 1429-1436); and do not kill normal HLA-A2-positive NOD/SCID engrafting hematopoietic stem cells (Gao et al (2003) Transplantation 75, 1429-1436). However, none of these publications give molecular information concerning the TCR present in the CTL, and the particular CTL line mentioned in the publications has not been made available to the public in any way and so the structure of the TCR is unknown and could not be derived by the skilled person (since the CTL line was not publicly available).